Electromechanical vibrators

ABSTRACT

1,119,911. Vibratory electric motors. DERRITRON Ltd., P. GROOTENHUIS, and J. W. GEARING. 26 Oct., 1965 [28 Oct., 1964], No. 44034/64. Heading H2A. The moving coil of a powerful vibrator has internal passages for cooling fluid. The coil is arranged in two coaxial layers 16, 17 of conductors which are either spaced by longitudinal spacers (18, Figs. 2, 3, not shown) to leave passages 19 between them, or as shown, flattened longitudinal tubes 21 are interposed between the layers. Bracing rods 22 may extend between header members at top and bottom of the coil. Air, water or refrigerant fluid may be used. A re-cycling cooling system is described. The cooling passages may be helical and may be in several layers.

April 30, 1968 P. GROOTENHUIS ETAL 3,380,515

ELECTROMECHANICAL VIBRATORS Filed Oct. 24, 1965 2 Sheets-Sheet l JAMES W GEAEING PETER GEOCTENHUIS ATTORNEYS April 30, 1968 P. GROOTENHUIS ETAL 3,380,515

ELECTROMECHANICAL VIBRATORS 2 Sheets-Sheet 2 Filed Oct. 24, 1965 lNveN-rolas JAMES W. GEAQWG I PETER GEoaTENHuis BY M Can- Toew Eff;

United States Patent 0 ELECTROMECHANICAL VIBRATORS Peter Grootenhuis, London, and James Walter Gearing, St. Leonards-on-Sea, England, assignors to Derritron Limited, London, England, a company of Great Britain Filed Oct. 24, 1965, Ser. No. 504,728 Claims priority, application Grjat Britain, Oct. 28, 1964, 44,03 10 Claims. (Cl. 165-40) ABSTRACT OF THE DISCLOSURE This invention relates to improved moving coil elements that vibrate axially in an annular air gap between inner and outer pole pieces of a magnet in electromechanical vibrators. The moving coil comprises two tubular layers of conductors coaxially mounted one within the other with supporting means between them in the form of spacer elements to permit coolant to be circulated through the moving coil element itself.

This invention relates to moving coil electromechanical vibrators. Such vibrators usually include a pot magnet having an inner pole piece surrounded by an annular outer pole piece affording between them an annular air gap to receive a moving coil carried by a tubular support connected to an output member supported so as to be capable of axial vibration with the coil. Such vibrators may be of considerable size capable of exerting forces of hundreds of pounds and may therefore consume a considerable amount of power. The present invention is concerned with facilitating the cooling of the moving coil.

According to the present invention the moving coil of a moving coil electromechanical vibrator includes two tubular layers of conductors lying coaxi-ally one within the other, leaving passages for cooling fluid extending through the annular space between them from one end to the other. A series of spacers are preferably provided situated in the annular space between the layers of conductors. In one form of the invention the spacers are of tubular form and constitute passages for coolant. In an alternative arrangement the spacers have gaps between them to constitute the coolant passages. In either case the spacers are preferably secured to the layers of conductors, and with them may form a substantially self supporting structure rat-her than relying primarily on a separate former. For example the conducting layers and spacers may be partially encapsulated in a synthetic resin so as together to form an integral self supporting structure.

The invention may be put into practice in various ways but two specific embodiments will be briefly described by Way of example with reference to the accompanying drawings in which:

FIGURE 1 is a schematic diagram showing a vibrator with a cooling system embodying the invention,

FIGURE 2 is a sectional detail of the coil in the vibrator of FIGURE 1,

FIGURE 3 is a sectional view on the line III-III in FIGURE 2, and

FIGURE 4 is a perspective sectional view of a vibrator coil according to another embodiment of the invention.

As shown in FIGURE 1, the vibrator has a pot magnet 11 with a coil assembly 12 extending into the annular gap 13 defined by the pot magnet. The coil assembly 12 is supported from an output member 14 extending proud of the vibrator casing 15 and able to vibrate with the coil assembly in the direction of the axis of the annular gap 13.

In place of the usual moving coil comprising a conduct- "ice ing winding wound on the outside of a tubular former, the arrangement, in accordance with the invention employs a coil consisting of two co-axial tubular layer windings 16 and 17, shown best in FIGURE 2, supported and spaced apart by a number of longitudinal spacers 18 (FIGURE 3). The spacers are in the form of solid bars of rectangular section which are spaced apart circumferentially so as to leave gaps 19 between them.

In the modification of FIGURE 4 the spacers are in the form of flattened circular section as shown at 21 with the radial dimension less than the circumferential dimension. Although they can be spaced apart circumferentially they are shown in the preferred arrangement in FIGURE 4 as abutting one another so as to occupy the whole of the annular space 19 between the two layers 16 and 17 of the winding. In each case the spacers extend parallel with the axis of the coil.

In either case the coil may be built up in any convenient manner. For example the inner winding 16 may be wound on a temporary former or mandrel after which the spacers 18 or 21 are applied to it and the outer winding 17 is wound about the spacers. The complete structure may then be impregnated with a synthetic resin so as to bond each winding into a solid tube and bond the windings to the spacers so as to form a strong self-supporting structure. Additional structural members, for example, axially extending pres-tressing rods 22 (FIGURE 4) may be included in place of, or between, certain of the spacers and either they or the spacers or both may be used to connect the moving coil assembly to the output member 14.

The prestressing rods 22 may be secured at one end to a member 23 defining with the output member 14 a cooling fluid gallery and at the other end to a member 24 defining another cooling fluid gallery or possibly to a clamping ring.

The passages formed through the tubular spacers or between the solid spacers extending from end to end of the coil are employed for circulation of cooling fluid such as air or water, and the shape of their cross-section is chosen to achieve the appropriate heat transfer characteristics. If the current-carrying conductors are of circular section a superior heat transfer characteristic is obtained with solid spacer bars, whereas if the current carrying conductor is of rectangular section tubular spacers are preferred.

The cooling circuit may be arranged in various ways. In one arrangement the coolant is supplied through a flexible pipe to the upper gallery whence it flows down through all the cooling passages to the lower coolant gallery from which it is extracted through a further flexi ble pipe. In a second arrangement there is no lower coolant gallery and the coolant, after entering and flowing down the cooling passages as before, escapes freely from their bottom ends to a reservoir space in the lower part of the vibrator, whence it can be scavenged in a conventional way. Thirdly the coolant may flow from the upper gallery down only certain of the passages to their lower ends where it is diverted by a collecting gallery and/or baflies so as to flow up through a similar number of adjacent passages into a second gallery at the upper end. The last arrangement renders the coolant inlet and outlet pipes readily accessible.

The arrangement described facilitates the incorporation of temperature measuring devices such as thermocouples for monitoring and control of the temperature of the current-carrying conductors.

The cooling system is shown diagrammatically in FIG- URE 1 in which a pump 26 circulates coolant through a radiator 27 cooled by a fan unit 28 to a connection block 29 on the vibrator casing and then through a flexible pipe 30 to the upper gallery; After fiowing through the cooling passages in the coil assembly, the coolant leaves through another flexible pipe 31 and connection block 32, and returns to the pump through a non-return valve 33, a flow switch 34, and a filter 35. The system includes a header tank 36 coupled to the input side of the pump through a make-up valve 37 and to the downstream side of the pump through a drain valve 38. A thermocouple is shown diagrammatically at 35 juxtaposed and secured to a part of the assembly in the area defined by the several conductors and is connected through electrical connections shown diagrammatically at 41 to a control 42 on a ump.

It will be appreciated that the construction described enables the coolant flowing in each passage to extract heat from two surfaces simultaneously. It requires little or no additional space as compared with the usual former conductor Winding, and yet provides passages for cooling fluid with little or no loss of rigidity or strength. Since the spacers do not provide a closed circumferential path they may be formed of metal, providing a strong supporting structure without interfering with the electromagnetic properties of the system. Since there are a large number of cooling passages the likelihood of complete blockage is remote, and high coolant flow velocities can be used without undue pressure losses in the system. The latter is a particular advantage when refrigerant fluids are circulated direct from a refrigeration cooling plant. The constuction described is moreover capable of withstanding comparatively high pressures associated with the use of refrigerant fluids as coolant.

It will be appreciated that the invention is not restricted to the details of the specific embodiments described. Thus while the coil preferably embodies a number of longitudinally extending spacers bet-Ween inner and outer windings the latter may be spaced and supported by other forms of spacing structure, in particular by bars or tubes extending along a coarse pitched helix. Moreover more than two layers of conductors may be employed, forming more than one annular space.

What we claim as our invention and desire to secure by Letters Patent is:

1. A moving coil electromechanical vibrator including a magnet having an inner pole piece and an annular outer pole piece mounted in spaced radial relationship to form an anular air gap therebetween, a moving coil located in the air gap, an output member secured to the moving coil by a coil support member, and suspension means mounting the output member and moving coil to enable axial movement of the moving coil in the air gap, the moving coil comprising, two tubular layers of electrical conductors positioned co-axially one within the other and radially spaced from each other to form an annular space therebetween, and the coil support member being positioned at least partially within the annular space and being formed to provide at least one passage extending substantially parallel to the moving coil axis through the annular space to allow flow of a coolant.

2. An electromechanical vibrator according to claim 1 wherein the moving coil further comprises a plurality of head conductive spacer elements positioned in the annular space between the two tubular layers of electrical conductors.

3. An electromechanical vibrator according to claim 2 wherein the spacer elements have an opening to form coolant passages having an elliptical cross-sectional shape, and the coolant passages extend substantially parallel to the longitudinal axis of the moving coil.

4. An electromechanical vibrator according to claim 3 wherein the moving coil further comprises a number of supporting rods located between adjacent spacer elements at pre-selected intervals around the circumference of the annular space, and the supporting rods form the coil support member.

5. An electromechanical vibrator according to claim 2 wherein the spacer elements are solid and are positioned in the annular space in non-abutting relationship to one another to form coolant passages extending substantially parallel to the longitudinal axis of the moving coil.

6. \An electromechanical vibrator according to claim 2 wherein the spacer elements and the two layers of electrical conductors form a substantially self-supporting integral structure.

7. An electromechanical vibrator according to claim 6 wherein the spacer elements form the coil support memher.

8. An electromechanical vibrator according to claim 7 further including a coolant gallery for retaining a coolant and wherein the annular space is connected at least at one end with the coolant gallery.

9. An electromechanical vibrator according to claim 1 further comprising coolant supply and circulating means, and conduit means connecting the supply and circulating means and the annular space to provide coolant to and from the at least one passage to remove heat from the moving coil.

10. An electromechanical vibrator according to claim 9 wherein the moving coil further comprises temperature sensing means located in juxtaposition to the annular space defined by said conductors toprovide control signals to regulate the flow of coolant to and from the moving coil.

References Cited UNITED STATES PATENTS 2,083,611 6/1937 Marshall -40 X 2,773,202 12/ 1956 Jacobs et a1. 310- 184 X 2,898,484 8/ 1959 Krastehew 310-64 X FOREIGN PATENTS 789,726 l/ 1958 Great Britain.

ROBERT A. OLEARY, Primary Examiner.

T. W. STREULE, Assistant Examiner. 

